[英]How do I create a delegate to assign to the onClick event of a dynamic menu?
我想做以下,但我收到错误争论类型DoWindow
不能分配给参数System.EventHandler
如何让我的委托从System.EventHandler
继承?
public delegate void DoWindow(MdiLayout layoutInstruction) ;
private ToolStripMenuItem MakeWindowMenu()
{
var tsi = new ToolStripMenuItem("Window");
tsi.DropDownItems.Add(CreateMenuItem("Cascade","Cascade the features", DoWindowLayout(MdiLayout.Cascade)));
tsi.DropDownItems.Add(CreateMenuItem("Tile Vertical","Tile the features vertically", this.DoWindowTileVertically));
//etc
return tsi;
}
private ToolStripMenuItem CreateMenuItem(string Caption, string tooltip, EventHandler onClickEventHandler)
{
var item = new ToolStripMenuItem(Caption);
item.Click += onClickEventHandler;
item.ToolTipText = tooltip;
return item;
}
public DoWindow DoWindowLayout(MdiLayout layoutInstruction)
{
Master.MDIForm.LayoutMdi(layoutInstruction);
}
您可以使用Action
作为参数,并使用匿名Eventhandler
来调用Action
就像是:
private ToolStripMenuItem MakeWindowMenu()
{
var tsi = new ToolStripMenuItem("Window");
tsi.DropDownItems.Add(CreateMenuItem("Cascade", "Cascade the features", () => Master.MDIForm.LayoutMdi(MdiLayout.Cascade)));
tsi.DropDownItems.Add(CreateMenuItem("Tile Vertical", "Tile the features vertically", () => { }));
return tsi;
}
private ToolStripMenuItem CreateMenuItem(string Caption, string tooltip, Action onClickEventHandler)
{
var item = new ToolStripMenuItem(Caption);
item.Click += (s, e) => { onClickEventHandler.Invoke(); };
item.ToolTipText = tooltip;
return item;
}
您的自定义EventHandlers需要包含方法的必需签名。 换句话说:ToolStripMenuItemClick需要一个带签名的方法
delegate void EventHandler(object Sender, EventArgs e);
所以你需要改变你的委托的签名和相应的方法。
请参阅此处以供进一步参考
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